Extracorporeal Membrane Oxygenation (ECMO) for Refractory Cardiac Arrest

Audience Our target audience includes emergency medicine residents/physicians. Introduction Treating cardiac arrest is a common theme during simulated emergency medicine training; however, less time is focused on treating refractory cases of cardiac arrest. There are varying definitions of refractory cardiac arrest, but it is most commonly defined as the inability to obtain return of spontaneous circulation (ROSC) after 10–30 minutes of appropriate cardiopulmonary resuscitation (CPR).1,2 More specifically, refractory ventricular fibrillation (VF) is defined as VF persisting despite 3 shocks, or the combination of 3 unsuccessful shocks plus amiodarone.1,3 Extracorporeal Membrane Oxygenation (ECMO) is becoming an increasingly utilized tool in the emergency department for severe cases of both pulmonary and cardiovascular pathology, and has been shown to be successful in cases of refractory cardiac arrest. Using ECMO in this scenario is known as Extracorporeal Cardiopulmonary Resuscitation (ECPR), referring to the emergent implementation of veno-arterial (VA) ECMO, and data have shown significantly improved neurologically-intact survival compared to routine CPR.3–7 Educational Objectives Our objectives go beyond the basics of advanced cardiac life support (ACLS), forcing the learner to think about alternative treatments for refractory cardiac arrest. By the end of this session, the learner should be able to: Recognize refractory cardiac arrest and realize when advanced management is required beyond the basics of ACLS Recite the indications/contraindications to ECMO Differentiate the physiology and clinical requirements between using venous-venous (VV) ECMO for respiratory failure, and using VA ECMO for cardiovascular failure Identify the anatomical cannulation sites for VV vs VA ECMO Perform the procedural skills to cannulate for both VV and VA ECMO Educational Methods This simulation is flexible. We used a high-fidelity mannequin with the “Endo-Circuit” to practice cannulating for ECMO, but the learning objectives can still be achieved with a lower-fidelity mannequin and cannulation device. The “Endo-Circuit” is a novel, low-cost vascular model developed by Dr Tomoyuki Endo from Sendai, Japan to practice ECMO cannulation.8,9 Endo-Circuit: Author’s own image Alternatively, a lower-fidelity model can be utilized if the Endo-Circuit is not available. We recommend using clear silicone tubing, which can be found at your local hardware store. This tubing should be at least 12mm in internal-diameter to accommodate the large ECMO catheters. We cut the tubing into 6-inch pieces so they could easily be swapped out for multiple participants to practice cannulating, all in a cost-effective manner. Red and blue tape was applied to differentiate the artery from the vein. Low-fidelity tubing: Author’s own image We split our educational session into different stages. The first stage included the high-fidelity mannequin without the Endo-Circuit because we did not want to reveal our ultimate goal of starting the patient on ECMO by having the tubing overlying the mannequin. Neither standard ACLS methods nor advanced medications for refractory cardiac arrest lead to achieving ROSC in this scenario. Stage 1 ends when the learners suggest starting the patient on ECMO and call the appropriate consultants. After a short debrief on stage 1, we then transition to a 2nd mannequin that we had in the back of the room. This mannequin had the Endo-Circuit overlying, and everything was covered with a sheet, again so as not to reveal the goal of the simulation from the beginning. On this 2nd mannequin, we practiced cannulating for VA ECMO in the setting of cardiac arrest. Below are photos of the ECMO cannulation kit, the cannulated Endo-Circuit, as well as the cannulated lower-fidelity silicone tubing. ECMO Cannulation Kit: Author’s own image Cannulated Endo-Circuit: Author’s own image Cannulated low-fidelity silicone tubing: Author’s own image Research Methods The learners filled out a post-simulation survey, which included questions specifically focused on the educational objectives (as mentioned above). We used a 1–5 Likert scale ranging from strongly disagree (1) to strongly agree (5) to quantify how the residents’ understanding of the learning objectives improved after the simulation. This survey also included questions taken directly from the Debriefing Assessment for Simulation in Healthcare (DASH), which is a validated evaluation tool developed by the Center for Medical Simulation (CMS) for evaluating the efficacy of the educational content.10 The DASH scoring system involves a 7-point scale ranging from extremely ineffective/detrimental (1) to extremely effective/outstanding (7). Results Thirty-one resident-learners participated in the simulation, and we received 22 survey responses. All of the learning objectives obtained a mean score >4 out of 5, with the exception of improving the learners’ differential diagnosis for refractory cardiac arrest, which received a mean score of 3.86. The most successful of the learning objectives was improving the learners’ procedural skills for ECMO cannulation, which received a mean score of 4.68. The DASH questions also reflected the success of the simulation, with 3 of the 6 questions receiving a mean score >6 out of 7, and the other 3 questions receiving a score >5. Discussion According to this data, the learners found the simulation to be effective in expanding their knowledge base and improving procedural skills for starting critically-ill patients in refractory cardiac arrest on ECMO. Practicing the cannulation procedure on the Endo-Circuit was shown to be the most useful aspect of this simulation. The DASH survey questions further demonstrate that our methods created an engaging, structured environment to identify knowledge gaps and simultaneously fill them using hands-on, active learning. Topics Extracorporeal membrane oxygenation, ECMO, cardiac arrest, refractory cardiac arrest, V fib, ventricular fibrillation, CPR, cardiopulmonary resuscitation, ECPR, extracorporeal cardiopulmonary resuscitation, ACLS, advanced cardiac life support, HOCM, hypertrophic obstructive cardiomyopathy, critical care, emergency medicine.


Linked objectives and methods:
This simulation is split into 4 stages. Stage 1 involved the learners running the code using the ACLS algorithm, identifying this to be a case of refractory ventricular fibrillation, and thus forcing them to think beyond the ACLS algorithm, eventually reaching for other options in their clinical tool-belt such as ECMO. Stage 1 was aimed at fulfilling Objective 1 above. Once the learners suggest starting ECMO and call the appropriate consultants, the simulation is paused, allowing time to debrief the code (this is Stage 2). This leads into Stage 3, which involves transitioning to the 2 nd mannequin with the Endo-Circuit and/ or other cannulation device. During Stage 3, the instructor introduces Objectives 2-5, briefly going through the indications/contraindications to starting ECMO, explaining the physiology behind VV vs VA ECMO, and then demonstrating, step by step on the mannequin, how to perform cannulation for the different ECMO scenarios. Stage 4 involves active, hands-on learning by having the trainees perform the cannulation procedure, while thinking about the anatomy of the cannulation sites (venous vs arterial), to help reinforce the physiology behind ECMO, and gain a better understanding of the indications to utilize VV vs VA strategies in differing clinical scenarios.
Starting a patient on ECMO is clearly a high-stakes scenario, and it is inappropriate for a learner to practice initiation for the first time during a real patient-encounter. This simulation helps to build the foundational knowledge of when and how to initiate a patient on ECMO and allows the learners to apply this knowledge using hands-on procedural learning by practicing the appropriate cannulation techniques. All of this is accomplished in a controlled, low-risk, engaging learning environment. The goal is to allow the learners to make mistakes and improve upon their clinical skills during the simulation, so that they are better prepared to take care of critically-ill patients while on shift in the real world.

Recommended pre-reading for instructor:
The following resources were useful to prepare for the simulation:

Learner responsible content:
• The learners would benefit from the same resources provided for the instructors, noted above.
Results and tips for successful implementation: 31 resident-learners participated in the simulation, and we received 22 post-simulation survey responses (71% response rate). The first 5 questions aimed to evaluate the educational content of the simulation. We used a 1-5 Likert scale ranging from "strongly disagree (1)" to "strongly agree (5)" to measure how well the simulation improved the following clinical and procedural skills: The next 6 questions were taken directly from the DASH questionnaire (Debriefing Assessment for Simulation in Healthcare), and were focused on assessing the methodology of the simulation in achieving the learning objectives. The DASH scoring system involves a 7-point scale ranging from "extremely ineffective/detrimental (1)" to "extremely effective/outstanding (7)." Overall, these results indicate a high level of success in achieving our learning objectives through the simulation. The learners indicated that the most useful part of the simulation session was the hands-on aspect of practicing the cannulation techniques for ECMO. The lowest score among the first 5 questions related to the differential diagnosis of refractory cardiac arrest. Therefore, more time could have been spent on this topic during the debrief session during Stage 2 of the stimulation. The DASH questions further validate our educational methods for the simulation, achieving greater than 6/7 for the first 3 questions, and greater than 5/7 for the next 3 questions.
If we were to do this simulation again, we would recommend having the learners perform both a pre-survey, as well as a post-survey, and to have the learners complete these at the time of the training, which will help increase the number of participants who filled out the survey.

Acknowledgement:
We would like to extend an extra-special thank you to Dr. Tomoyuki Endo for allowing us to use his innovative Endo-Circuit. We applaud his work in continuing to improve ECPR, as well as his dedication to education and simulation in order to expand the utility of ECMO in the emergency department.

Confederates needed:
This simulation needs at least one confederate to act as the paramedic, who will summarize the pre-hospital events and transition care to the ED team. A narrator in the simulation control room would also be helpful. We had the learners play all other roles including team leader, airway physician, cannulating physician (all eventually get to practice this role during stage 3), nurse/techs as needed.

Disposition:
Disposition to the ICU after ECMO cannulation.